Fish-gathering blocks of various types (box-shaped and cylindrical, for instance) have heretofore been used to form artificial fish shelters. The conventional blocks have been apt to sink in the sea-bottom in a short period of time after installation under the action of ocean-currents known as scouring. For instance, a conventional box-shaped block is exemplified in FIGS. 1A through 1D. When a current W impinges on a fish-gathering block 10 at the sea-bottom, that portion of the current which flows in the vicinity of the lower part of the block 10 becomes deflected downward. This deflected current W.sub.a then excavates the earth and sand around the block 10. After some time, the block 10 may overturn or, otherwise, sink in the sea-bottom 9 as shown in FIG. 1D, thus losing the function of the fish-gathering block.
The object of this invention is to provide such a fish-gathering block of new design which is capable of solving the aforementioned problems as experienced with conventional blocks, which is superb in fish-gathering effect, and which is easy to manufacture, transport and install.
Being mostly of large size, conventional one-piece fish-gathering blocks are difficult to manufacture, transport and install on the sea-bottom. Such difficulties are obviated by dividing each block into several elemental members and assembling such members where the block is to be installed.